Generators are often used in certain situations to feed electrical power to residential and commercial load circuits during a utility power outage. As set forth in FIG. 1 and as understood to be conventional in power transfer devices, a portable generator 104 is typically connected to a power inlet box 106 mounted to an exterior wall of a building. The power inlet box 106 is further electrically connected to a transfer switching mechanism 108 that continues the electrical path through circuit breakers associated with the transfer switching mechanism 108 to supply power to certain selected circuits or breakers of the load circuit 110 in the main switch panel as determined by the transfer switching mechanism circuit breakers. The circuits of the transfer switching mechanism 108 are wired to selected circuits of the load center, through wiring housed within a conduit extending between the load center and the transfer switching mechanism 108. Thus, through manual operation of the switches in the transfer switching mechanism 108, a user of the system can select between utility power supplied to the load circuit through a utility meter 102 and generator power supplied by the generator 104 to power the selected circuit of the load center. As an example, during a utility power outage, a user may start up the generator 104 and manual switch the input electrical power from utility power to generator power in order to restore power to pre-designated, critical circuits (e.g., hot-water heater, refrigerator).
Typically, in the transfer switching mechanism 108, the utility power is controlled by a utility power switch and the generator power is controlled by a generator power switch. Often, the utility power switch and the generator power switch are functionally linked via an interlock device such that both switches cannot both be in the ON position at the same time, thus, preventing both the utility and the generator from simultaneously supplying power to the load center and overloading the load circuits, potentially damaging the circuits. The interlock device may physically link the utility power switch and the generator power switch such that turning one switch to the ON position forces the other switch to the OFF position. On the other hand, the interlock device may simply block both switches from being in the ON position at the same time while not aiding in the physical switching of the switches. In the case of the interlock devices physically linking the utility power switch and the generator power switch, the interlock device may cause the utility power switch and the generator power switch to act as a “break-before-make” (“BBM”) switch. As the name implies, a BBM switch breaks a certain circuit before making or connecting a new circuit. In one example of an interlock device functioning as a BBM switch, as a user manually switches the generator power switch to the ON position, and, subsequently, the utility power switch to the OFF position, the interlock device breaks the circuit connection with the utility power before making a connection with the generator power. This prevents both power sources providing power to the load circuits and potentially damaging the circuits. While certain interlock devices may be known, there is room for improvement.
With these thoughts in mind, among others, aspects of the manual transfer switch interlock device, disclosed herein, were conceived.